Organic light-emitting display device and method of manufacturing the same

ABSTRACT

An organic light-emitting display device includes a thin film transistor (TFT) including an active layer, a gate electrode, a source electrode, and a drain electrode, the thin film transistor includes at least one of a switching TFT and a driving TFT. A pixel electrode is connected to one of the source electrode or the drain electrode. An auxiliary electrode is spaced apart from the TFT and the pixel electrode. An intermediate layer is disposed on at least a portion of the pixel electrode and on at least a portion of the auxiliary electrode. A first electrode is disposed on at least a portion of the intermediate layer and on at least a portion of the auxiliary electrode. A second electrode, which directly contacts an upper surface of the auxiliary electrode, is disposed on the first electrode. A contact hole exposes at least a portion of the auxiliary electrode.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/938,943 filed Jul. 10, 2013, which claims the benefit of KoreanPatent Application No. 10-2013-0020020, filed on Feb. 25, 2013, in theKorean Intellectual Property Office, the disclosure of which isincorporated herein in its entirety by reference.

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND

1. Field

The present disclosure relates to an organic light-emitting displaydevice and a method of manufacturing the same.

2. Description of the Related Technology

An organic light-emitting display apparatus typically includes anorganic light-emitting diode (OLED) including a hole injectionelectrode, an electron injection electrode, and an organic emissionlayer between the hole and electron injection electrodes. The organiclight emitting display apparatus is generally a self-emissive displayapparatus in which light is emitted while excitons generated when holesinjected by the hole injection electrode and electrons injected by theelectron injection electrode are combined in the organic emission layertransit from an excited state to a ground state.

The organic light-emitting display device that is the self-emittingdisplay device does not require an additional light source. Therefore,the organic light-emitting display device is driven at a low voltage, ismade light and thin, has a wide view angle, a high contrast, and a fastresponse speed. Also, according to high-quality properties, the organiclight emitting display device is receiving attention as a nextgeneration display device.

In particular, in an active organic light-emitting display device havinga top emission structure, light from an organic emission layer isemitted toward a common electrode. The common electrode is formed to bemaximally thin. As the common electrode is thin, a resistance increases,and a voltage drops.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

According to an aspect of the present invention, there is provided anorganic light-emitting display device including: a substrate includingfirst and second areas; a pixel electrode of the substrate; an auxiliaryelectrode of the substrate; an intermediate layer including an organicemission layer and formed on the pixel electrode formed in the firstarea and the auxiliary electrode formed in the second area; a firstcommon electrode formed on the intermediate layer; and a second commonelectrode formed on the first common electrode, wherein the secondcommon electrode and the auxiliary electrode contact each other througha contact hole which penetrates the first common electrode and theintermediate layer formed on the auxiliary electrode.

The intermediate layer formed on the auxiliary electrode may include afirst contact hole exposing the auxiliary electrode. The first commonelectrode formed on the auxiliary electrode may include a second contacthole exposing the auxiliary electrode.

The first and second contact holes may be formed in the same size.

A thickness of the second common electrode may be larger than athickness of the first common electrode.

The auxiliary electrode may be formed on the same layer as the pixelelectrode.

The auxiliary electrode may include the same material as the pixelelectrode.

The first and second common electrodes may have a light transmittingproperty and include magnesium (Mg) and silver (Al).

The pixel electrode may be a reflective electrode.

According to another aspect of the present invention, there is providedan organic light-emitting display device including: a substrate; a thinfilm transistor (TFT) formed on the substrate and including an activelayer, a gate electrode, a source electrode, and a drain electrode; anorganic light-emitting diode (OLED) in which a pixel electrode, anintermediate layer, and a common electrode are stacked, wherein thepixel electrode is electrically connected to one of the source and drainelectrodes, the intermediate layer includes an organic emission layer,and the common electrode faces the pixel electrode and includes firstand second common electrodes; and an auxiliary electrode which is formedon the same layer as the pixel electrode, wherein the second commonelectrode and the auxiliary electrode contact each other through acontact hole which penetrates the first common electrode and theintermediate layer formed on the auxiliary electrode.

A thickness of the second common electrode may be larger than athickness of the first common electrode.

The auxiliary electrode and the pixel electrode may include the samematerial.

Light emitted from the OLED may be emitted toward the common electrode.

According to another aspect of the present invention, there is provideda method of manufacturing an organic light-emitting display device,including: providing a substrate including first and second areas;forming a pixel electrode in the first area of the substrate; forming anauxiliary electrode in the second area of the substrate; forming anintermediate layer including an organic emission layer on the pixelelectrode and the auxiliary electrode; forming a first common electrodeon the intermediate layer; forming a contact hole in a positioncorresponding to the second area to expose the auxiliary electrode; andforming a second common electrode on the first common electrode so thatthe second common electrode contacts the auxiliary electrode through thecontact hole.

The formation of the contact hole may include: simultaneously formingfirst and second contact holes, wherein the first contact holepenetrates the intermediate layer formed on the auxiliary electrode andthe second contact hole penetrates the first common electrode formed onthe auxiliary electrode.

The first and second contact holes may substantially have the same size.

The formation of the contact holes may be performed in an atmosphere ofan inert gas.

The formation of the contact hole may include: forming contact holespenetrating the first electrode and the intermediate layer formed on theauxiliary electrode by using a laser drilling method.

The formation of the pixel electrode and the formation of the auxiliaryelectrode may be simultaneously performed.

The auxiliary electrode may include the same material as the pixelelectrode.

The auxiliary electrode and the pixel electrode may include a metalhaving a reflective property.

The formation of the first common electrode and the formation of thesecond common electrode may be performed in a vacuum.

The formation of the second common electrode may include: forming thesecond common electrode thicker than the first common electrode.

The formation of the first common electrode may include: forming thefirst common electrode including Mg and Al.

The formation of the second common electrode may include: forming thesecond common electrode including Mg and Al.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail certain embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a schematic cross-sectional view illustrating an organiclight-emitting display device according to an embodiment of the presentinvention;

FIGS. 2 through 7 are cross-sectional views illustrating a process ofmanufacturing an organic light-emitting display device according to anembodiment of the present invention;

FIG. 8 is a schematic cross-sectional view illustrating an organiclight-emitting display device as a comparison example;

FIG. 9 is a graph illustrating leakage current density-voltage (J-V)properties of an organic light-emitting display device according toembodiments of the present invention;

FIG. 10 is a graph illustrating leakage current density-voltage (J-V)properties of an organic light-emitting display device as comparisonexamples; and

FIG. 11 is a graph illustrating leakage current density-voltageproperties of an organic light-emitting display device according toembodiments of the present invention and leakage current density-voltage(J-V) properties of an organic light-emitting display device ascomparison examples.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

While certain embodiments are capable of various modifications andalternative forms, embodiments thereof are shown by way of example inthe drawings and will herein be described in detail. It should beunderstood, however, that there is no intent to limit exampleembodiments to the particular forms disclosed, but on the contrary,example embodiments are to cover all modifications, equivalents, andalternatives falling within the scope of the invention. It will beunderstood that, although the terms first, second, third etc. may beused herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. The terminology used herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting of example embodiments. As used herein, the singular forms“a,” “an” and “the” are intended to include the plural forms as well,unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises” and/or “comprising” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof “/” used belowmay be interpreted as “and” or “or” according to situations. In thedrawings, the thicknesses of layers and regions may be exaggerated forclarity. Like reference numerals in the drawings generally denote likeelements. It will be understood that when an element, such as a layer, aregion, or a substrate, is referred to as being “on” or “above” anotherelement, it may be directly on, or intervening elements may be present.

FIG. 1 is a schematic cross-sectional view illustrating an organiclight-emitting display device according to an embodiment of the presentinvention.

Referring to FIG. 1, the organic light-emitting display device includesa substrate 110 which comprises first and second areas A1 and A2 and onwhich a device/line (DL) layer is formed. An organic light-emittingdiode (OLED) 170 is formed in a position corresponding to the first areaA1 of the substrate 10 and includes a pixel electrode 171, anintermediate layer 172 including an organic emission layer, and a commonelectrode 173. An auxiliary electrode 190 is formed in a positioncorresponding to the area A2. The auxiliary electrode 190 may beincluded per one sub-pixel or per one pixel. The common electrode 173includes first and second common electrodes 173 a and 173 b. Theintermediate layer 172 and the first and second common electrodes 173 aand 173 b are disposed on the pixel electrode 171 of the OLED 170 andthe auxiliary electrode 190. Also, the auxiliary electrode 190 contactsthe second common electrode 173 b.

The substrate 110 may be a flexible substrate and may be formed of aplastic having high heat-resistance and durability properties. However,the present invention is not limited thereto, and thus the substrate 110may be formed of various types of materials such as metal, glass, etc.

A buffer layer 120 is formed on the substrate 110. The buffer layer 120is to form a flat surface on the substrate 110 and prevent impurityelements from permeating into the substrate 110. The buffer layer 120may be formed of a silicon nitride and/or a silicon oxide as a singlelayer or multiple layers

The DL layer includes a driving thin film transistor (TFT) 130 drivingthe OLED 170, a capacitor 140, a switching TFT (not shown) electricallyconnected to the capacitor 140, and lines connected to the driving TFT130 or the switching TFT or the capacitor 140. The driving TFT 130 isshown in FIG. 1 to be electrically connected to the OLED 170 in order tosupply a current to the OLED 170. However, the organic light-emittingdisplay device may also include the switching TFT electrically connectedto the capacitor 140, as described above.

The driving TFT 130 may include an active layer 131, a gate electrode132, a source electrode 133 s, and a drain electrode 133 d. A gateinsulating layer 150 is interposed between the gate electrode 132 andthe active layer 131 to insulate the gate electrode 132 and the activelayer 131 from each other. Source and drain areas 131 s and 131 d dopedwith high-density impurities are formed at both edges of the activelayer 131 so that a channel area 131 c is formed between the source anddrain areas 131 s and 131 d. The active layer 131 may include amorphoussilicon, polysilicon, and oxide semiconductor.

The source and drain electrodes 133 s and 133 d are formed above thegate electrode 132 and a first interlayer insulating layer 151 is formedbetween the gate electrode 132 and the source and drain electrodes 133 sand 133 d. The source and drain electrodes 133 s and 133 d may berespectively electrically connected to the source and drain areas 131 sand 131 d of the active layer 131. A second interlayer insulating layer152 is formed on the source and drain electrodes 133 s and 133 d. A linelayer 160 may be formed along with the source and drain electrodes 133 sand 133 d without an additional process for forming the line layer 160.

A top gate type TFT is shown in FIG. 1, but the present invention is notlimited thereto. According to another embodiment, a bottom gate type TFTmay be applied.

The capacitor 140 recharges a signal applied to the driving TFT 130 evenafter the switching TFT is switched off. The capacitor 140 includesfirst and second electrodes 141 and 142, and the first interlayerinsulating layer 151 is interposed as a dielectric layer between thefirst and second electrodes 141 and 142. The first electrode 141 of thecapacitor 140 may be formed on the same layer as the gate electrode 132,and the second electrode 142 may be formed on the same layer as thesource and drain electrodes 133 s and 133 d. The first electrode 141 isformed together with the gate electrode 132, and the second electrode isformed together with the source and drain electrodes 133 s and 133 d,thereby reducing the number of processes.

The OLED 170 is disposed in the first area A1 of the substrate 110 andincludes the pixel electrode 171, the common electrode 173, and theintermediate layer 172. The pixel electrode 171 is electricallyconnected to one of the source and drain electrodes 133 s and 133 d ofthe driving TFT 130, and the common electrode 173 is disposed oppositeto the pixel electrode 171. The intermediate layer 172 includes theorganic emission layer and is interposed between the pixel electrode 171and the common electrode 173.

The organic emission layer may include a low or high molecular organicmaterial. If the organic emission layer includes the low molecularorganic material, the intermediate layer 172 may further include a holetransport layer (HTL) and a hole injection layer (HIL) which are formedtoward the pixel electrode 171 based on the low molecular organicmaterial. Also, the intermediate layer 172 may further include anelectron transport layer (ETL) and an electron injection layer (EIL)which are formed toward the common electrode 173. In addition to theselayers, the intermediate layer may further various types of layers. Ifthe organic emission layer includes the high molecular organic material,the intermediate layer 172 may further include only the HTL toward thepixel electrode 171. The organic emission layer may form one unit pixelof sub pixels emitting red (R), green (G), and blue (B) lights.Alternatively, the organic emission layer may form one unit pixel of subpixels emitting R, G, B, white (W) lights.

The pixel electrode 171 may include a metal having a light reflectiveproperty to be formed as a reflective electrode, and the commonelectrode 173 may have a light transmitting property. Therefore, theorganic light-emitting display device may be formed as a top emissiontype. A metal having a low work function, e.g., Ag, Mg, Al, Pt, Pd, Au,Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/Al, or a compound thereof, may bedeposited to form the reflective electrode.

The common electrode 173 may be formed by depositing Al to be a thinlayer. Alternatively, the common electrode 173 may be formed bydepositing a compound of Ag and Mg to be a thin layer. The commonelectrode 173 may have a thickness of about 100 Å or less to have thelight transmitting property. The common electrode 173 includes the firstand second common electrodes 173 a and 173 b. The first and secondcommon electrodes 173 a and 173 b may include the same material.However, the first common electrode 173 a is thinner than the secondcommon electrode 173 b to improve a processing property when formingcontact holes H1 and H2 that will be described later.

The organic light-emitting display device is classified into a topemission type and a bottom emission type according to a realizationdirection of an image. In the top emission type, the image is realizedfrom the pixel electrode 171 toward the common electrode 173. In thebottom emission type, the image is realized from the common electrode173 toward the pixel electrode 171. The top emission type has a higheraperture ratio than the bottom emission type. The common electrode 173is used as a transparent electrode such as an Indium Tin Oxide (ITO) inorder to realize an image toward a front. However, the transparentelectrode mostly has a high resistance, and thus an IR drop phenomenonoccurs. Therefore, the common electrode 173 may have the lighttransmitting property and include a metal having a relative lowresistance like Ag, Mg, or the like. However, the common electrode 173is formed on a front surface of the substrate 110 and has a relativelythin thickness as described above in order to improve the lighttransmissivity. Therefore, an IR drop phenomenon may still occur due toa resistance.

Accordingly, in order realize a top emission type having a higheraperture ratio and lower a high resistance of the common electrode 173,in the organic light-emitting display device according to oneembodiment, the auxiliary electrode 190 formed in the second area A2 ofthe substrate 110 forms a contact area contacting the common electrode173, in more detail, the second common electrode 173 b.

The auxiliary electrode 190 is formed on the same layer as the pixelelectrode 171 and is formed of the same material as the pixel electrode171. The auxiliary electrode 190 is formed as the same process as thepixel electrode 171, and thus the total number of processes is notincreased. For the contact between the auxiliary electrode 190 and thecommon electrode 173, a contact hole may be formed to expose theauxiliary electrode 190. For example, a contact hole H1 of theintermediate layer 172 and a contact hole H2 of the first commonelectrode 173 a are formed to expose the auxiliary electrode 190. Thecontact holes H1 and H2 are formed after the intermediate layer 172including the organic emission layer and the first common electrode 173a are formed. The auxiliary electrode 190 contacts the second commonelectrode 173 b through the contact hole (e.g., the contact holes H1 andH2) to improve the IR drop phenomenon. The second common electrode 173 bmay be relatively thicker than the first common electrode 173 a within arange that does not hinder the light transmitting property. Through thisstructure, a resistance of the second common electrode 173 b contactingthe auxiliary electrode 190 may be minimized to effectively improve theIR drop phenomenon.

Furthermore, the contact holes H1 and H2 of the organic light-emittingdisplay device according to one embodiment are formed after theintermediate layer 172 and the first common electrode 173 are formed,thereby minimizing an occurrence of a leakage current caused by anunstable interface of the intermediate layer 172 and particles formedwhen the contact holes H1 and H2 are formed. This will be described inmore detail later with reference to FIGS. 8 and 11. A method ofmanufacturing the organic light-emitting display device according to anembodiment will now be described in detail with reference to FIGS. 2through 7. The method includes a process of forming the contact holes H1and H2 and a process of allowing the auxiliary electrode 190 to contactthe second common electrode 173 b.

FIGS. 2 through 7 are cross-sectional views illustrating a method ofmanufacturing the organic light-emitting display device, according to anembodiment of the present invention.

Referring to FIG. 2, the substrate 110 including first and second areasmay be provided. The buffer layer 120 and the DL layer are formed on thesubstrate 110.

In more detail, the buffer layer 120, a semiconductor layer for formingthe active layer 131, the gate insulating layer 150, and a first metallayer (not shown) are sequentially formed on the substrate 110. Andthen, the first metal layer is patterned to form the gate electrode 132and the first electrode 141 of the capacitor 140.

The semiconductor layer may be formed of amorphous silicon orpolysilicon. The amorphous silicon may be crystallized to form thepolysilicon. The amorphous silicon may be crystallized according tovarious methods such as a rapid thermal annealing (RTA) method, a solidphase crystallization (SPC) method, an excimer laser annealing (ELA)method, a metal induced crystallization (MIC) method, a metal inducedlateral crystallization (MILC) method, a sequential lateralsolidification (SLS) method, etc. According to another embodiment, thesemiconductor layer may include an oxide semiconductor as describedabove. An inorganic insulating layer such as SiNx or SiOx may bedeposited according to a plasma enhanced chemical vapor deposition(PECVD) method, an atmosphere pressure CVD (APCVD), method, a lowpressure CVD (LPCVD), or the like to form the gate insulating layer 150

The first metal layer is patterned to form the gate electrode. The gateelectrode 132 is used as a self-aligning mask to dope the semiconductorlayer with n-type or p-type dopant in order to form the active layer 131including the source and drain areas 131 s and 131 d and the channelarea 131 c interposed between the source and drain areas 131 s and 131d.

The first interlayer insulating layer 151 is deposited, and then asecond metal layer (not shown) is formed and patterned to form thesource and drain electrodes 133 s and 133 d, the second electrode 142 ofthe capacitor 140, and the line layer 160.

The first interlayer insulating layer 151 may be formed of one or moreorganic insulating materials selected from the group consisting ofpolyimide, polyamide, acryl resin, benzocyclobutene, and phenol resinaccording to a spin coating method or the like. The first interlayerinsulating layer 151 may be formed of an inorganic insulating materialsuch as SiN_(x) or SiO_(x) according to a PECVD method, an APCVD method,an LPCVD method, or the like. Alternatively, an organic insulating layerand an inorganic insulating material may alternate with each other toform the first interlayer insulating layer 151.

The second interlayer insulating layer 152 is deposited, and then athird metal layer (not shown) is formed and patterned to form the pixelelectrode 171 in a position corresponding to the first area and theauxiliary electrode 190 in a position corresponding to the second area.The pixel electrode 171 is electrically connected to the drain electrode133 d through an opening formed in the second interlayer insulatinglayer 152.

Like the first interlayer insulating layer 151, the second interlayerinsulating layer 152 may include an organic insulating material and/oran inorganic insulating material. The third metal layer may be formed bydepositing material selected from the group consisting of Ag, Mg, Al,Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/Al, or a compoundthereof. Since the third metal layer is patterned to simultaneously formthe pixel electrode 171 and the auxiliary electrode 190, an additionalprocess is not required, and the auxiliary electrode 190 and the pixelelectrode 171 are formed of the same material on the same layer.

A pixel defined layer (PDL) 180 is formed between the pixel electrode171 and the auxiliary electrode 190.

The PDL 180 may be formed of one or more organic insulating materialsselected from the group consisting of polyimide, polyamide, acryl resin,benzocyclobutene, and phenol resin according to a spin coating method orthe like. The PDL 180 may be formed of an inorganic insulating materialselected from SiO₂, SiN_(x), Al₂O₃, CuO_(x), Tb₄O₇, Y₂O₃, Nb₂O₅, andPr₂O₃ in addition to an organic insulating material as described above.The PDL 180 may be formed in a multilayer structure in which an organicinsulating material and an inorganic insulating material alternate witheach other.

After the PDL 180 is entirely formed, a mask process is performed toform the opening in order to expose the auxiliary electrode 190 and thepixel electrode 171. The PDL 180 has a predetermined thickness to widena gap between an edge of the pixel electrode 171 and the commonelectrode 173 of FIG. 1 in order to prevent an electric field from beingconcentrated on the edge of the pixel electrode 171. Therefore, a shortbetween the pixel electrode 171 and the common electrode 173 isprevented.

Referring to FIG. 3, the intermediate layer 172 including the organicemission layer is formed on entire parts of the pixel electrode 171 andthe auxiliary electrode 190. The intermediate layer 172 is formed in theopening exposing the pixel electrode 171 and the auxiliary electrode 190and may be deposited according to an evaporation method by using a lowor high molecular organic material in a vacuum.

If the organic emission layer includes a low molecular organic material,the intermediate layer 172 may further include the HTL and the HIL whichare formed toward the pixel electrode 171 based on the low molecularorganic material. Also, the intermediate layer 172 may further includethe ETL and the EIL which are formed toward the common electrode 173. Inaddition to these layers, various types of layers may be furtherincluded. If the organic emission layer includes a high molecularorganic material, the intermediate layer 172 may further include onlythe HTL toward the pixel electrode 171 as described above.

Referring to FIG. 4, the first common electrode 173 a is formed on theintermediate layer 172.

The first common electrode 173 a may be formed of Al or may be formed toinclude Ag or Mg. For example, Al may be deposited in a vacuum to formthe first common electrode 173 a. According to another embodiment, Agand Mg may be simultaneously deposited in a vacuum to form the firstcommon electrode 173 a. The first common electrode 173 a may be thinnerthan the second common electrode 173 b to improve a processing propertywhen forming the second contact hole H2.

Referring to FIGS. 5 and 6, the contact holes (e.g., contact holes H1and H2) are formed to expose the auxiliary electrode 190.

According to a laser drilling method, the contact holes H1 and H2 areformed in the intermediate layer 172 and the first common electrode 173a, respectively. In order to control particles generated when formingthe contact holes H1 and H2, in an atmosphere of an inert gas such asnitrogen or argon, the first contact hole H1 penetrating theintermediate layer 172 and the second contact hole H2 penetrating thefirst common electrode 173 a may be formed by using a laser L. The firstand second contact holes H1 and H2 are simultaneously formed by usingthe same laser L, and thus sizes of the first and second contact holesH1 and H2 may be substantially the same.

If the contact holes H1 and H2 are formed by using the laser L in avacuum atmosphere, it is difficult to control the particles generatedwhen forming the contact holes H1 and H2. Therefore, the contact holesH1 and H2 may be formed in an atmosphere of an inert gas. However, as alarge portion of the organic emission layer is exposed to the inert gas,an interface of the organic emission layer, i.e., an interface of theorganic emission layer contacting the inert gas, becomes unstable,thereby generating a leakage current. Also, a life and an efficiencyproperty of the organic light-emitting display device are lowered.

However, according to an embodiment, the first common electrode 173 a isformed, and then the contact holes H1 and H2 are formed. Therefore, anarea of the organic emission layer exposed to the inert gas is only anexposed degree of the organic emission layer through the contact holesH1 and H2. Therefore, the unstability of the interface of the organicemission layer is minimized, and the generation of the leakage currentis minimized.

Referring to FIG. 7, the second common electrode 173 b is formed on thefirst common electrode 173 a to contact the auxiliary electrode 190through the contact holes H1 and H2.

The second common electrode 173 b may be formed of Al or may be formedto include Ag and Mg. For example, by depositing Al in a vacuum, thesecond common electrode 173 b may be formed. According to anotherembodiment, Al and Mg may be simultaneously deposited in a vacuum toform the second common electrode 173 b.

The common electrode 173 including the first and second commonelectrodes 173 a and 173 b is to have a light transmitting property, andthus increasing a thickness of the common electrode 173 is limited.However, the second common electrode 173 b contacting the auxiliaryelectrode 190 may be thicker than the first common electrode 173 awithin a range that does not hinder the light transmitting property, toprevent an electric resistance from being increased.

Properties of the organic light-emitting display device of the presentinvention and of an organic light-emitting display device that is acomparison example will now be described with reference to FIGS. 8through 11.

FIG. 8 is a cross-sectional view illustrating a part corresponding to asecond area of an organic light-emitting display device that is acomparison example.

Referring to FIG. 8, an organic emission layer 72 is formed on anauxiliary electrode 90 in a vacuum, a contact hole H is formed in anatmosphere of an inert gas by using a laser drilling method to penetratethe organic emission layer 72, and then a common electrode 73 is formedin a vacuum. Therefore, the organic light-emitting display device of thecomparison example is different from the organic light-emitting displaydevices of the present invention in this point.

FIG. 9 is a graph illustrating leakage current density-voltage (J-V)properties of an organic light-emitting display device according toembodiments of the present invention. FIG. 10 is a graph illustratingleakage current density-voltage (J-V) properties of an organiclight-emitting display device as comparison examples. FIG. 11 is a graphillustrating leakage current density-voltage properties of an organiclight-emitting display device according to embodiments of the presentinvention and leakage current density-voltage (J-V) properties of anorganic light-emitting display device as comparison examples. In thegraphs, a unit of a voltage is V, and a unit of a leakage currentdensity is A/cm².

Referring to FIGS. 9 through 11, the organic light-emitting displaydevice according to the embodiments of the present invention shows arelatively stable property without a leakage current.

Meanwhile, referring to FIGS. 10 through 11, as to the organiclight-emitting display device as the comparison example, the graphs showV shapes and the leakage current density is greatly changed in a sectionin which a voltage is between 0V and 3V.

In the organic light-emitting display device according to an embodimentof the present invention, the intermediate layer 172 including theorganic emission layer and the first common electrode 173 a are formed,and then the contact hole is formed. Therefore, a deterioration of aproperty of the interface of the organic emission layer is minimized.

According to an embodiment of the present invention as described above,there may be provided a top emission type organic light-emitting displaydevice in which an auxiliary electrode contacts a second commonelectrode to improve an aperture ratio and minimize an IR drop.

Also, there may be provided an organic light-emitting display device inwhich an organic emission layer and a first common electrode are formed,and then contact holes are formed to allow an auxiliary electrode tocontact a second electrode in order to minimize a leakage current andrealize a high-quality image.

While the present invention has been particularly shown and describedwith reference to certain embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

What is claimed is:
 1. An organic light-emitting display devicecomprising: a thin film transistor (TFT) including an active layer, agate electrode, a source electrode, and a drain electrode, the thin filmtransistor includes at least one of a switching TFT and a driving TFT; apixel electrode connected to one of the source electrode or the drainelectrode; an auxiliary electrode spaced apart from the TFT and thepixel electrode; an intermediate layer disposed on at least a portion ofthe pixel electrode and on at least a portion of the auxiliaryelectrode; a first electrode disposed on at least a portion of theintermediate layer and on at least a portion of the auxiliary electrode;a second electrode disposed on the first electrode; and a contact holeexposing at least a portion of the auxiliary electrode; wherein thesecond electrode directly contacts an upper surface of the auxiliaryelectrode.
 2. The organic light-emitting display device of claim 1,wherein the intermediate layer includes an organic emission layer. 3.The organic light-emitting display device of claim 1, wherein athickness of the second electrode is larger than a thickness of thefirst electrode.
 4. The organic light-emitting display device of claim1, wherein the auxiliary electrode is formed on the same layer as thepixel electrode.
 5. The organic light-emitting display device of claim1, wherein the auxiliary electrode comprises the same material as thepixel electrode.
 6. The organic light-emitting display device of claim1, wherein the first and second electrodes have a light transmittingproperty and comprise magnesium (Mg) and silver (Al).
 7. The organiclight-emitting display device of claim 1, wherein the pixel electrode isa reflective electrode.
 8. The organic light-emitting display device ofclaim 1, wherein the contact hole is connected to the upper surface ofthe auxiliary electrode.